lapd detective mark fuhrman joins us. in terms of investigation, at this point what do we need to know and why? we know who did it, and he's dead. there's no suspicion that there is a co-conspirator out there or that he had help. yet, you know, we're obsessively going after this. why? >> well, greta, you have to do it just as a matter of protocol. you have to match up all the ballistics for every bullet that's comparable to that fire arm. you have to do that. you have to do the forensics, the toxicology on the shooter, make sure the shooter's gun was actually the gun that was used to kill himself. you have to put all these pieces of the puzzle together because you really don't know where this is going to go. you don't know if somebody could have actually been in contact with adam lanza and actually gave him the idea or was in a chat room and really kind of prodded him into this crime. you don't know where it's going, and i think that's why they're so aggressive. >> all right. what could possibly be on the hard drive? why